Dual-Row Magnetic Field Sensor for Misalignment Error Reduction
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Solution Overview
Problem
Magnetic field sensors used to detect the rotation angle of a magnet often suffer from errors due to misalignment between the sensor and the magnet, particularly between the magnetic field sensing elements and the magnet, leading to inaccuracies in the sensed angle.
Innovation Solution
A magnetic field sensor design featuring two rows of magnetic field sensing elements, such as GMR elements, arranged on opposite sides of a rotation axis, with electronic channels to generate signals indicative of the magnet's angle, which are combined to reduce errors caused by misalignment and provide a relative angle value of the magnet's rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single row of magnetic field sensing elements is used, then the device structure is simple, but measurement precision deteriorates due to misalignment errors
Solution Approach 1:
The sensor array is divided into two separate rows of magnetic field sensing elements positioned on opposite sides of the rotation axis. Each row independently measures magnetic field components, and the results are combined through signal processing to eliminate misalignment errors. This segmentation allows the system to achieve high measurement precision while maintaining a relatively simple overall structure.
2Measurement precision
If two rows of magnetic field sensing elements are used, then measurement precision improves by reducing misalignment errors, but device complexity increases
Solution Approach 1:
The measurements from both rows of sensing elements are merged through signal processing operations (such as differencing or integrating). This combining of data from multiple sources cancels out misalignment errors while the physical structure remains relatively simple with elements arranged in just two rows on opposite sides of the rotation axis.
3Adaptability or versatility
If CVH elements are used to generate angle signals, then angle detection capability is achieved, but measurement precision deteriorates due to inherent errors and misalignment sensitivity
Solution Approach 1:
The patent converts the harmful effect of misalignment into a beneficial cancellation effect. By positioning sensing elements symmetrically on opposite sides and combining their signals, the misalignment errors that would normally degrade precision are transformed into canceling components, leaving only the true angle information. This approach maintains angle detection capability while eliminating the precision problems associated with CVH elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sensor achieves reduced errors in angle detection due to misalignment, providing accurate rotation angle measurements by differencing or integrating signals from both rows of sensing elements, effectively improving the precision of magnetic field sensing.
Implementation Method 1
Hall Effect elements generate an output voltage proportional to a magnetic field
Implementation Method 2
magnetoresistance elements change resistance in proportion to a magnetic field
Implementation Method 3
Hall Effect elements generate an output voltage proportional to a magnetic field
Implementation Method 4
magnetoresistance elements change resistance in proportion to a magnetic field. In a circuit, an electrical current can be directed through the magnetoresistance element, thereby generating a voltage output signal proportional to the magnetic field
Data Source
AI summary
A magnetic field sensor has first and second rows of magnetic field sensing elements coupled to an electronic circuit. A magnet can be disposed under or over the magnetic field sensor. The magnetic field sensor is operable to use the first and second rows of magnetic field sensing elements and the electronic circuit to detect a relative rotation angle between the magnet and the first and second rows of magnetic field sensing elements.